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Synapomorphy
In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxon, taxa and is therefore Hypothesis#Scientific hypothesis, hypothesized to have evolved in their most recent common ancestor. ) In cladistics, synapomorphy implies Homology (biology), homology. Examples of apomorphy are the presence of Terrestrial locomotion#Posture, erect gait, fur, Evolution of mammalian auditory ossicles, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a Terrestrial locomotion#Posture, sprawling gait and lack of fur. Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals. Etymology The word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autapomorphy
In phylogenetics, an autapomorphy is a distinctive feature, known as a Synapomorphy, derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or Outgroup (cladistics), outgroup taxa, not even those most closely related to the focal taxon (which may be a species, family (biology), family or in general any clade). It can therefore be considered as an apomorphy in relation to a single taxon. The word ''autapomorphy'', introduced in 1950 by German entomology, entomologist Willi Hennig, is derived from the Greek language, Greek words αὐτός, ''autos'' "self"; ἀπό, ''apo'' "away from"; and μορφή, ''morphḗ'' = "shape". Discussion Because autapomorphies are only present in a single taxon, they do not convey information about relationship. Therefore, autapomorphies are not useful to infer phylogenetic relationships. However, autapomorphy, like synapomorphy and plesiomorphy is a relative concept depending on the ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synapomorphy
In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxon, taxa and is therefore Hypothesis#Scientific hypothesis, hypothesized to have evolved in their most recent common ancestor. ) In cladistics, synapomorphy implies Homology (biology), homology. Examples of apomorphy are the presence of Terrestrial locomotion#Posture, erect gait, fur, Evolution of mammalian auditory ossicles, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a Terrestrial locomotion#Posture, sprawling gait and lack of fur. Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals. Etymology The word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lamprey
Lampreys (sometimes inaccurately called lamprey eels) are a group of Agnatha, jawless fish comprising the order (biology), order Petromyzontiformes , sole order in the Class (biology), class Petromyzontida. The adult lamprey is characterized by a toothed, funnel-like sucking mouth. The common name "lamprey" is probably derived from Latin , which may mean "stone licker" ( "to lick" + "stone"), though the etymology is uncertain. "Lamprey" is sometimes seen for the plural form. About 38 extant species of lampreys are known, with around seven known extinct species. They are classified in three families—two small families in the Southern Hemisphere (Geotriidae, Mordaciidae) and one large family in the Northern Hemisphere (Petromyzontidae). Genetic evidence suggests that lampreys are more closely related to hagfish, the only other living group of jawless fish, than they are to jawed vertebrates, forming the superclass Cyclostomi. The oldest fossils of stem-group lampreys are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symplesiomorphy
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and synapomorphy all mean a trait shared between species because they share an ancestral species. Apomorphic and synapomorphic characteristics convey much information about evolutionary clades and can be used to define taxa. However, plesiomorphic and symplesiomorphic characteristics cannot. The term ''symplesiomorphy'' was introduced in 1950 by German entomologist Willi Hennig. Examples A backbone is a plesiomorphic trait shared by birds and mammals, and does not help in placing an animal in one or the other of these two clades. Birds and mammals share this trait because both clades are descended from the same far distant ancestor. Other clades, e.g. snakes, lizards, turtles, fish, frogs, all have backbones and none are either birds n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiomorphy
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral Phenotypic trait, character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy and synapomorphy, apomorphy, and synapomorphy all mean a trait shared between species because they share an ancestral species. Apomorphic and synapomorphic characteristics convey much information about evolutionary clades and can be used to define taxa. However, plesiomorphic and symplesiomorphic characteristics cannot. The term ''symplesiomorphy'' was introduced in 1950 by German Entomology, entomologist Willi Hennig. Examples A backbone is a plesiomorphic trait shared by birds and mammals, and does not help in placing an animal in one or the other of these two clades. Birds and mammals share this trait because both clades are descended from the same far distant ancestor. Other clades, e.g. snakes, lizards, turtles, fish, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apomorph
In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have evolved in their most recent common ancestor. ) In cladistics, synapomorphy implies homology. Examples of apomorphy are the presence of erect gait, fur, the evolution of three middle ear bones, and mammary glands in mammals but not in other vertebrate animals such as amphibians or reptiles, which have retained their ancestral traits of a sprawling gait and lack of fur. Thus, these derived traits are also synapomorphies of mammals in general as they are not shared by other vertebrate animals. Etymology The word —coined by German entomologist Willi Hennig—is derived from the Ancient Greek words (''sún''), meaning "with, together"; (''apó''), meaning "away from"; and (''morphḗ''), meaning "shape, form". Determining ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiomorphy And Symplesiomorphy
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and synapomorphy all mean a trait shared between species because they share an ancestral species. Apomorphic and synapomorphic characteristics convey much information about evolutionary clades and can be used to define taxa. However, plesiomorphic and symplesiomorphic characteristics cannot. The term ''symplesiomorphy'' was introduced in 1950 by German entomologist Willi Hennig. Examples A backbone is a plesiomorphic trait shared by birds and mammals, and does not help in placing an animal in one or the other of these two clades. Birds and mammals share this trait because both clades are descended from the same far distant ancestor. Other clades, e.g. snakes, lizards, turtles, fish, frogs, all have backbones and none are either birds no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothesis
A hypothesis (: hypotheses) is a proposed explanation for a phenomenon. A scientific hypothesis must be based on observations and make a testable and reproducible prediction about reality, in a process beginning with an educated guess or thought. If a hypothesis is repeatedly independently demonstrated by experiment to be true, it becomes a scientific theory. In colloquial usage, the words "hypothesis" and "theory" are often used interchangeably, but this is incorrect in the context of science. A working hypothesis is a provisionally-accepted hypothesis used for the purpose of pursuing further progress in research. Working hypotheses are frequently discarded, and often proposed with knowledge (and warning) that they are incomplete and thus false, with the intent of moving research in at least somewhat the right direction, especially when scientists are stuck on an issue and brainstorming ideas. A different meaning of the term ''hypothesis'' is used in formal l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek Dark Ages, Dark Ages (), the Archaic Greece, Archaic or Homeric Greek, Homeric period (), and the Classical Greece, Classical period (). Ancient Greek was the language of Homer and of fifth-century Athens, fifth-century Athenian historians, playwrights, and Ancient Greek philosophy, philosophers. It has contributed many words to English vocabulary and has been a standard subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Homeric Greek, Epic and Classical periods of the language, which are the best-attested periods and considered most typical of Ancient Greek. From the Hellenistic period (), Ancient Greek was followed by Koine Greek, which is regar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenotypic Trait
A phenotypic trait, simply trait, or character state is a distinct variant of a phenotypic characteristic of an organism; it may be either inherited or determined environmentally, but typically occurs as a combination of the two.Lawrence, Eleanor (2005) ''Henderson's Dictionary of Biology''. Pearson, Prentice Hall. For example, having eye color is a ''character'' of an organism, while blue, brown and hazel versions of eye color are ''traits''. The term ''trait'' is generally used in genetics, often to describe the phenotypic expression of different combinations of alleles in different individual organisms within a single population, such as the famous purple vs. white flower coloration in Gregor Mendel's pea plants. By contrast, in systematics, the term ''character state'' is employed to describe features that represent fixed diagnostic differences among taxa, such as the absence of tails in great apes, relative to other primate groups. Definition A phenotypic trait is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. The process of evolution has given rise to biodiversity at every level of biological organisation. The scientific theory of evolution by natural selection was conceived independently by two British naturalists, Charles Darwin and Alfred Russel Wallace, in the mid-19th century as an explanation for why organisms are adapted to their physical and biological environments. The theory was first set out in detail in Darwin's book ''On the Origin of Species''. Evolution by natural selection is established by observable facts about living organisms: (1) more offspring are often produced than can possibly survive; (2) phenotypic variatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrapod
A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetrapoda (). Tetrapods include all Neontology#Extant taxa versus extinct taxa, extant and Extinction, extinct amphibians and amniotes, with the latter in turn Evolution, evolving into two major clades, the Sauropsida, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (extinct pelycosaur, "pelycosaurs", therapsids and all extant mammals, including Homo sapiens, humans). Hox gene mutations have resulted in some tetrapods becoming Limbless vertebrate, limbless (snakes, legless lizards, and caecilians) or two-limbed (cetaceans, sirenians, Bipedidae, some lizards, kiwi (bird), kiwis, and the extinct moa and elephant birds). Nevertheless, they still qualify as tetrapods through their ancestry, and some retain a pair of ves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
